Screw presses for dewatering manure and other sludge materials are well known in the art. An example of a dewatering press used in the dairy industry is the press screw separator PSS 3.3-780 GB sold by FAN Separator GmbH of Marktschorgast, Germany and described in German patent DE 42 32 449 B4 granted to FAN Separator GmbH on Jun. 23, 2005. The beneficial impact of dewatering and reusing manure for cow bedding is also well known in the art, see for example the article by Jean Bonhotal et al. of the Cornell Waste Management Institute of Cornell University's College of Agriculture and Life Sciences, Ithaca, N.Y., titled “Dairy Manure Solids Cut Bedding Costs” published in Northeast Dairy Business, 10(4):24-25, 2008, as well as the article titled “Health Impacts and Economics of Using Dried Manure Solids in the Northeast” by M. C. Schwarz et al. presented at the Ninth Annual Fall Dairy Conference, Liverpool, N.Y. on Nov. 12-13, 2008.
A screw press for dewatering drilling mud in the petroleum industry is disclosed in U.S. Pat. No. 5,996,484 in which the screen is vibrated in the embodiment of FIG. 12 using a vibrator 140 with a view to increase dewatering efficiency.